Can Notre Dame ever be fully restored?
On Tuesday a piece of history was devastated - as fire ripped through the roof of Notre Dame and toppled its spire the world was left mortified.
The fire broke out shortly before 7pm European time, and was brought under control at around 3am, it took another six hours to be fully extinguished.
Though the roof and spire were destroyed the twin towers, once the tallest structures in Paris before the construction of the Eiffel Tower, remain safe - and the stained glass rose windows are also believed to have escaped major damage.
French President Emmanuel Macron has already pledged to rebuild the most-visited monument in his country and has promised to bring in the best talents from around the world to do so.
We take a look at the scale of the restoration and rebuilding project.
Can it ever be restored?
In short - yes. One of the problems in restoring the building to the exact specifications prior to April 15 is the lack of materials.
Bertrand de Feydeau, vice president of preservation group Fondation du Patrimoine, told France Info radio that the wooden roof that went up in flames was built with beams more than 800 years ago from primal forests.
He said the cathedral's roof cannot be rebuilt exactly as it was before the fire because "we don't, at the moment, have trees on our territory of the size that were cut in the 13th century".
He said the restoration work will have to use new technologies in order to rebuild the roof.
So the design would be different?
Well, fundamentally yes. Though whether or not it would be a rebuilding remains to be seen. Experts are now examining the remains of the building to see which parts of the structure are safe. Any designs or blueprints would depend entirely on the evaluation.
However, Peter Riddington, consulting director with Donald Insall Associates was part of the team that restored Windsor Castle following the 1992 fire.
“My feeling is that the history of the cathedral is so strong that to rebuild it in a form that isn’t what people understand Notre-Dame to be, what it symbolises and what they believe it to be would be a very difficult argument to win,” he said.
How much will it cost?
Cost will depend on design, so it can’t be determined. However, Mr Macron has said that he will launch a public subscription service to help raise funds and two businessmen have already pledged large amounts.
Bernard Arnault and his luxury goods group LVMH have pledged 200 million euro (£173 million) towards the reconstruction of Notre Dame, following a reported 100 million euro (£86 million) donation from another French billionaire, Francois Pinault.
It is estimated that the Vatican has holdings worth $10 to $15bn according to bankers estimates in Time Magazine - suggesting that there’s more than enough money to help the rebuilding project.
How long will it take?
Mr Riddington said the number of variables make it difficult to predict. In early TV interviews it was suggested a rebuild could take at least 10 years but until surveys have been carried out it is too difficult to predict.
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Is this a unique project?
No, there have been projects on a similar scale in the UK.
Windsor Castle was wrecked by fire on November 20 1992.
A £36.5 million repair project involving 1,500 building workers saw the 14th-century building reopen in 1997.
Mr Riddington said: “While Notre-Dame and Windsor will be similar in many ways, there are significant differences.
“This is a place of worship, Windsor was cellular rooms. This will probably be a much bigger rebuild, one of the great losses will be the glass
“Cathedrals do burn down but they are restored.
“With Windsor we finished around six months ahead of schedule and came in at 2/3 of the price - there is nothing like working for a monarch, or in this case a cathedral, to motivate people to get the very best out of them.
“People will want almost to pay to work on this - that’s not to say they will give their services for free but they will do things that are not economically advantageous.”
And York Minster was devastated by fire after being struck by lightening in July 1984.
More than 100 firefighters tackled the blaze, which caused £2.25 million in damage. The restoration work was completed in 1988.
What are experts saying?
While many people are pointing to Notre Dame surviving the French Revolution and the First and Second World Wars it has been damaged before.
Professor Sara Uckelman, a medieval historian at Durham University, said: “I'm finding that my background and training as a medievalist means I'm, overall, finding it a lot less devastating than many people.
“I know how churches live. They are not static monuments to the past. They are built, they get burned, they are rebuilt, they are extended, they get ransacked, they get rebuilt, they collapse because they were not built well, they get rebuilt, they get extended, they get renovated, they get bombed, they get rebuilt. It is the continuous presence, not the original structure, that matters.
“The spire that fell, that beautiful iconic spire? Not even 200 years old. A new spire can be built, the next stage in the evolution of the cathedral.
“Notre Dame is one of the best documented cathedrals in the world. We have the knowledge we need to rebuild it.
“But more than that: We have the skill. There may not be as many ecclesiastical stone masons nowadays as there were in the height of the Middle Ages, but there are still plenty, and I bet masons from all over Europe, if not further, will be standing ready to contribute to rebuilding. Same with glaziers, carpenters, etc.”